depot_tools: expose path to cros

Needed for https://codereview.chromium.org/1922503002

BUG=chromium:585401

Review URL: https://codereview.chromium.org/1917803002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@300135 0039d316-1c4b-4281-b951-d872f2087c98

recipe_modules/depot_tools/api.py

@@ -9,6 +9,10 @@ class DepotToolsApi(recipe_api.RecipeApi):
   def download_from_google_storage_path(self):
     return self.package_repo_resource('download_from_google_storage.py')
 
+  @property
+  def cros_path(self):
+    return self.package_repo_resource('cros')
+
   @property
   def gn_py_path(self):
     return self.package_repo_resource('gn.py')